This project seeks to demonstrate regional metabolic correlates of brain functional activity using the (14C) 2-deoxy-D-glucose (2-DG) autoradiographic method which reflects brain glucose utilization. Present projects include (A) the construction of an atlas which compares 2-DG autoradiographs from injected rat brains with corresponding labeled Nissl sections, and (B) use of 2-DG as a functional marker for the activity of the suprachiasmatic nucleus.